Latest Spring Flood Outlook

THIS OUTLOOK COVERS THE RED RIVER OF THE NORTH AND ITS MINNESOTA
AND NORTH DAKOTA TRIBUTARIES.

THIS 2010 SPRING FLOOD OUTLOOK FOR THE RED RIVER IS VALID FROM
FEBRUARY 24TH THROUGH MAY 25TH.

...ADVANCED HYDROLOGIC PREDICTION SERVICES/AHPS/ENABLE THE
NATIONAL WEATHER SERVICE TO PROVIDE LONG-RANGE PROBABILISTIC RIVER
OUTLOOKS...

...RED RIVER BASIN OUTLOOK FOR RIVER FLOOD POTENTIAL...

...MAJOR FLOODING IS LIKELY FOR MOST LOCATIONS ON THE MAINSTEM
OF THE RED RIVER OF THE NORTH AND MANY LOCATIONS ON ITS NORTH
DAKOTA TRIBUTARIES ACROSS SOUTHEASTERN NORTH DAKOTA...

LOCATIONS THAT HAVE A GREATER THAN 90% RISK OF REACHING OR
EXCEEDING MAJOR FLOOD STAGE ARE FARGO...ABERCROMBIE...LISBON...
HARWOOD AND WEST FARGO.

LOCATIONS THAT HAVE NEAR 50% OR GREATER RISK OF REACHING OR
EXCEEDING MAJOR FLOOD STAGE ARE WAHPETON...VALLEY CITY...
HALSTAD...GRAND FORKS...OSLO...DRAYTON AND PEMBINA ON THE RED
RIVER AND GRAFTON ON THE PARK RIVER.

DUE TO THE EXCESSIVE RAINFALL EXPERIENCED AGAIN LAST FALL...THE
AMOUNT OF WATER IN THE CURRENT SNOWPACK...AND THE PROSPECTS FOR
ADDITIONAL MOISTURE THROUGH THE SPRING SNOW-MELT PERIOD...THE
MAGNITUDE AND EXTENT OF SPRING 2010 FLOODING WILL LIKELY BE
SIMILAR TO THAT EXPERIENCED DURING THE SPRING OF 2009.

FALL RAINS WERE NEAR TO SLIGHTLY ABOVE NORMAL ACROSS MUCH OF
THE NORTHERN RED RIVER BASIN AND THE DEVILS LAKE BASIN. RAINFALL
AMOUNTS PUSHED TO NEAR 200 PERCENT OF NORMAL ACROSS THE RED RIVER
HEADWATERS AREA AND SOUTHERN-MOST PORTIONS OF THE BASIN.

CURRENT MOISTURE LEVELS IN THE SNOWPACK RANGE FROM 3 TO 5 INCHES
ACROSS THE NORTHERN HALF OF THE BASIN...AND RANGE FROM 4 TO 6
INCHES ACROSS THE SOUTHERN HALF. ISOLATED HEADWATERS AREAS HAVE
CLOSE TO 7 INCHES OF SNOW MOISTURE.

ANOTHER 1 TO 2 INCHES OF MOISTURE CAN BE EXPECTED THROUGH THE
REMAINDER OF THE WINTER PERIOD...INTO MID APRIL. INCREASED
MOISTURE ABOVE THESE LEVELS...LIKE THAT EXPERIENCED DURING THE
2009 SNOW-MELT PERIOD COULD INCREASE THE RISK OF MORE SEVERE
FLOODING AT MOST LOCATIONS ACROSS THE RED RIVER BASIN.

RESIDENTS ALONG STREAMS AND TRIBUTARIES IN THE SOUTHERN RED
RIVER BASIN...OR ALONG THE MAINSTEM OF THE RED RIVER...SHOULD BE
PREPARING FOR MAJOR FLOODING.

THE ST. PAUL DISTRICT OF THE US ARMY CORP OF ENGINEERS IS DOING A
MAXIMUM DRAWDOWN OF ALL THEIR FLOOD CONTROL RESERVOIRS IN THE RED
RIVER BASIN IN ADVANCE OF THE SPRING FLOOD MELT. THE NWS WILL BE
COORDINATING WITH THEM ON RELEASE SCHEDULES TO LESSEN THE FLOOD
IMPACTS DOWNSTREAM OF THESE RESERVOIRS.

THE FOLLOWING MESSAGE HAS TWO SECTIONS...THE FIRST GIVES THE CHANCES
OF RIVER LOCATIONS RISING ABOVE THEIR VARIOUS FLOOD STAGES AND THE
SECOND GIVES THE CHANCES OF RIVER LOCATIONS RISING ABOVE VARIOUS
STAGE VALUES.

...LONG-RANGE PROBABILISTIC RIVER OUTLOOK BY FLOOD CATEGORY...

THE TABLE BELOW GIVES THE CHANCES FOR EXCEEDING MINOR...MODERATE...
AND MAJOR FLOOD STAGES AT THE RIVER LOCATIONS LISTED DURING THE
VALID PERIOD INDICATED.

IN THE TABLE BELOW, THE 90 THROUGH 10 PERCENT COLUMNS GIVE THE CHANCE
THAT THE RIVER AT A CERTAIN LOCATION WILL RISE ABOVE THE STAGES
INDICATED BY THE VALUES IN THE ROW FOR THAT LOCATION ANYTIME DURING
THE NEXT 90 DAYS.

EXAMPLE: THE RED RIVER AT WAHPETON HAS A FLOOD STAGE OF 10 FEET.
IN THE NEXT 90 DAYS THERE IS A 50 PERCENT CHANCE THAT THE RED RIVER
AT WAHPETON WILL RISE ABOVE 14.4 FEET AND ONLY A 10 PERCENT CHANCE
THAT IT WILL RISE ABOVE 17.5 FEET.

...CURRENT HYDROLOGIC/CLIMATE CONDITIONS FOR THE RED RIVER OF THE
NORTH BASIN...

FALL PRECIPITATION WAS MUCH HIGHER THAN NORMAL IN THE UPPER
/SOUTHERN/ HALF OF THE BASIN. TOTALS AVERAGED 150 TO 300 PERCENT OF
THE MEAN FOR THIS TIME PERIOD. PRECIPITATION WAS NEAR NORMAL FOR THE
LOWER /NORTHERN/ PORTION OF THE BASIN. TEMPERATURES SEPTEMBER THROUGH
NOVEMBER WERE GENERALLY 2 TO 3 DEGREES ABOVE NORMAL.

ACCORDING TO THE USGS MONTHLY AVERAGE STREAMFLOW WAS ABOVE NORMAL
TO MUCH ABOVE NORMAL FOR SEPTEMBER AND OCTOBER IN THE SOUTHERN RED
RIVER VALLEY AND NEAR NORMAL IN THE NORTHERN PORTION. STREAMFLOWS
IN NOVEMBER WERE GREATER THAN THE 90TH PERCENTILE FOR THE ENTIRE
RED RIVER VALLEY.

PRECIPITATION DURING DECEMBER AND JANUARY WAS MUCH HIGHER THAN
NORMAL...150 TO 400 PERCENT OF THE MEAN AS TWO WINTER STORMS
MOVED THROUGH THE REGION.

NORTH DAKOTA...SOUTH DAKOTA...AND MOST OF MINNESOTA HAD MINIMAL
SNOW COVER THROUGH MUCH OF DECEMBER WITH PERIODS OF SUB-ZERO
TEMPERATURES. THIS COMBINED WITH HIGH SOIL MOISTURE CONTRIBUTED
TO DEEPER HARDER FROST FOR MANY AREAS. THESE CONDITIONS MAY
INCREASE RUNOFF POTENTIAL DURING THE SPRING THAW. FROST DEPTHS
IN THE RED RIVER VALLEY ARE GENERALLY 16 TO 28 INCHES.

SINCE FEBRUARY 1ST A PERSISTENT PRECIPITATION PATTERN HAS CONTINUED
TO MOVE THROUGH THE RED RIVER VALLEY. THE PRECIPITATION HAS BEEN
300 TO 400 PERCENT OF NORMAL...INCREASING THE WATER CONTENT OF
THE SNOW PACK.

MONTHLY AVERAGE STREAMFLOW REMAINED GREATER THAN THE 90TH PERCENTILE
FOR DECEMBER AND JANUARY.

THE U.S. DROUGHT MONITOR LONG-TERM DROUGHT INDICATOR SHOWS EXTREMELY
WET CONDITIONS ACROSS NORTH DAKOTA AND WESTERN MINNESOTA.

CURRENT MODELED SNOW WATER EQUIVALENTS AVERAGE 4 TO 5 INCHES IN THE
NORTH DAKOTA TRIBUTARIES AND THE MAINSTEM RED RIVER. SNOW WATER
EQUIVALENT AMOUNTS ON THE MINNESOTA TRIBUTARIES AVERAGE 3 TO 4
INCHES WITH AN AVERAGE BAND OF 4 TO 5 INCHES IN THE ROSEAU RIVER
BASIN. THE CURRENT AVERAGE SNOW DEPTH ACROSS THE BASIN IS GENERALLY
20 INCHES WITH A RANGE BETWEEN 10 AND 33 INCHES BASED UPON
OBSERVATIONS.

...CLIMATOLOGICAL OUTLOOK AND FORECAST CONDITIONS...

THE MOST RECENT CLIMATOLOGICAL OUTLOOKS FROM THE NWS CLIMATE
PREDICTION CENTER GIVE AN EQUAL CHANCE FOR ABOVE NORMAL/NORMAL/
BELOW NORMAL CONDITIONS FOR TEMPERATURE AND PRECIPITATION IN THE
RED RIVER BASIN. FORECAST WEATHER CONDITIONS INDICATE A RELATIVELY
DRY AND COOL PERIOD FOR THE NEXT WEEK.

THE OUTLOOK PRODUCTION PROCESS...

THIS LONG RANGE PROBABILISTIC OUTLOOK IS BASED ON A SERIES OF PEAK
RIVER LEVELS TAKEN FROM THE FORECAST RESULTS OF THE NWS ENSEMBLE
STREAMFLOW MODEL /ESF/. THE MODEL IS RUN FOR MULTIPLE SCENARIOS
USING CURRENT RIVER...SNOW AND SOIL CONDITIONS COMBINED WITH ABOUT
50 YEARS OF PAST PRECIPITATION AND TEMPERATURE CONDITIONS
EXPERIENCED DURING THE OUTLOOK PERIOD...AND COMPARED AGAINST CURRENT
SPRING TEMPERATURE AND PRECIPITATION OUTLOOKS.

PROVIDING A RANGE OF RIVER LEVEL PROBABILITIES BASED ON CURRENT
CONDITIONS AND PAST SPRING WEATHER...THE OUTLOOK GIVES EXPECTED
AMOUNTS OF RISK WHICH CAN THEN HELP WITH LONG RANGE FLOOD PLANNING
AND RESPONSE READINESS. THIS OUTLOOK IS A PART OF NOAA/S NATIONAL
WEATHER SERVICE/S AHPS/ADVANCED HYDROLOGIC PREDICTION SERVICES/.

FORECASTERS PRODUCE MULTIPLE SCENARIO HYDROGRAPHS USING THE ESF
MODEL INITIALIZED WITH RECENT RAIN/SNOW AND SOIL MOISTURE CONDITIONS
IN THE RED RIVER BASIN AND APPLYING SETS OF PAST PRECIPITATION AND
TEMPERATURES FOR THE YEARS 1948 THROUGH 2008 AND FOR THE VALID
PERIOD OF THE OUTLOOK.

ADDITIONAL INFORMATION SOURCES...

THE AHPS LONG RANGE PROBABILISTIC OUTLOOKS ARE ISSUED EACH MONTH
TYPICALLY BETWEEN THE FIRST AND SECOND FRIDAY AFTER MID-MONTH.
HOWEVER...SPRING FLOOD AND WATER RESOURCES OUTLOOKS ARE ISSUED
SEVERAL TIMES DURING THE CRITICAL SPRING MELT PERIOD...USUALLY
FROM EARLY MARCH TO EARLY APRIL...DEPENDING ON CONDITIONS.

THIS OUTLOOK IS ALSO PRESENTED AS GRAPHS OF THE PROBABILITY OF STAGE
EXCEEDANCE FOR THE FULL PERIOD AND FOR WEEKLY INTERVALS DURING THE
PERIOD. THESE GRAPHS AND EXPLANATIONS THAT HELP INTERPRETING THEM
ARE AVAILABLE FROM THE NWS GRAND FORKS AHPS WEB PAGE ON THE
INTERNET AT:
WWW.WEATHER.GOV/GRANDFORKS

THEN CLICK ON THE RIVERS AND LAKES AHPS LINK IN THE LEFT MENU.

CURRENT RIVER CONDITIONS FOR ALL RIVER FORECAST POINTS IN THE RED
RIVER OF THE NORTH AND DEVILS/STUMP LAKE CONDITIONS ARE ALSO
AVAILABLE ON OUR WEB SITE...AS WELL AS THE 7-DAY FORECASTS WHEN
THE RIVER AT THE FORECAST POINT IS IN OR NEAR FLOOD.

IF YOU HAVE ANY QUESTIONS...CONTACT THE NWS AT 701-772-0720.

A NEW...POINT SPECIFIC FLOOD BRIEFING WEB PAGE IS AVAILABLE AT:

WWW.CRH.NOAA.GOV/FGF/BRIEFING/FLOODBRIEFING.PHP /USE LOWER CASE/

...NEXT UPDATE AND ADDITIONAL INFORMATION...

THE NEXT OUTLOOK WILL BE ISSUED ON FRIDAY...MARCH 5TH...2010.
OTHERWISE...THEY WILL BE ISSUED MONTHLY THROUGHOUT THE REST OF THE
YEAR DURING THE LATER PART OF THE MONTH OR UPDATED AS CONDITIONS
WARRANT.

THE MAJOR FLOOD STAGE FOR THE RED RIVER OF THE NORTH AT HALSTAD
WILL BE LOWERED FROM 40 FEET TO 37.5 FEET ON MONDAY...MARCH 8TH.
CURRENTLY THERE IS ABOUT A 75% CHANCE FOR THE RIVER THERE TO
REACH OR EXCEEDING THE NEW MAJOR FLOOD STAGE.